This invention pertains to the art of wheelchairs and, more particularly, to adjustable wheelchairs. The invention applies to an adjustable wheelchair where the seat depth can be easily altered to ensure a proper, comfortable, and posturally correct seat that adapts to various seating and positioning systems, as well as dimensional changes as the user grows. The invention is particularly described with reference to a collapsible or folding lightweight wheelchair that is custom manufactured to meet the user's measurements and dimensional configuration. However, it will be appreciated that the invention has broader applications and may find application and use in related wheelchairs.
Folding wheelchairs usually pivot or collapse via a cross brace assembly that is connected to the seat and side frames. A cross brace assembly that has met with commercial success is shown and described in commonly owned U.S. Pat. No. 4,813,693, the details and disclosure of which are hereby incorporated by reference. The '693 patent describes a cross brace assembly in which upper ends of the cross brace members are integrally secured to first and second seat rails, respectively. The seat rails extend in parallel fashion along side edges or perimeter portions of the seating surface, typically supporting marginal edges of a collapsible seat material. Likewise, the seat back is also typically formed from a collapsible material so that when the wheelchair is folded, the material easily folds thereby allowing the side frames and accompanying wheels to be brought closer together in a collapsed condition for storage or transportation.
The '693 patent teaches a variety of adjustable features that allow the chair to accommodate a growing child. Thus, a telescopic arrangement allows the length of the seats to be increased but it is necessary to substitute the cross brace assembly with a new assembly since the cross members are integrally secured to the seat rails. Thus, even though the wheelchair is adjustable to accommodate the growth of a child or a new seating/positioning system, a new cross brace assembly is required to accommodate the change.
The subject invention is intended to adapt to a growing user or a new seating/positioning system while employing the same components to achieve this objective.